Refrigerator

ABSTRACT

In a refrigerator having a thermally insulating housing which surrounds a storage chamber and having a refrigerant circuit which comprises a compressor, a condenser, a restrictor and an evaporator which cools the storage chamber, the restrictor is arranged at least partially on a side wall of the housing.

The present invention relates to a refrigerator, in particular ahousehold refrigerator, having a thermally insulating housing, whichencloses a storage chamber for items to be chilled, and a refrigerantcircuit, which comprises a compressor, a condenser, a restrictor and anevaporator, which cools the storage chamber. The action of such a knownrefrigerator is based on the fact that the compressor sucks refrigerantin vapor form out of the evaporator and feeds the refrigerant, when ithas been heated adiabatically by compression, to the condenser, where itcondenses while emitting heat. The liquid refrigerant thus obtaineddecompresses as it passes through the restrictor and returns to theevaporator adiabatically cooled.

The extent of adiabatic cooling is a function of the pressure differencepassed through between condenser and evaporator. The warmer therefrigerant at the outlet of the condenser, the warmer it also is whenit reaches the evaporator after decompressing. Theoretically it ispossible to approximate the temperature of the refrigerant at the outletof the condenser to anywhere near the temperature of the environment, towhich the condenser emits its heat but the required dimensions of thecondenser have to be greater, the smaller this temperature difference isto be. The cooling that can be achieved at the condenser is also limitedby parasitic heat transfer between warm, upstream regions of thecondenser and cooler downstream regions. When air, which has alreadybeen heated in upstream regions of the condenser, flows around adownstream region of the condenser, said downstream region can no longercool the refrigerant to below the temperature of said air.

Refrigerators are known, in which a frame heater is provided to preventcondensation on the housing in the vicinity of a seal positioned betweencarcass and door of the housing. Such a frame heater comprises a tube,which is inserted into the refrigerant circuit between compressor andcondenser or downstream of the condenser, in order to heat the surfacesof the housing that are susceptible to condensation to above dew pointwith the compression heat of the refrigerant. As the susceptibility tocondensation stems from the thermal coupling of said surfaces to thecooled storage chamber, the heat released by the frame heater ultimatelyalso flows into the storage chamber to a significant extent, therebyhaving a detrimental effect on the energy efficiency of therefrigerator.

The object of the present invention is to improve the energy efficiencyof a refrigerator, in particular a household appliance.

The object is achieved in that with a refrigerator of the type definedin the introduction the restrictor is disposed at least partially on aside wall of the housing. Because of its small free cross sectioncompared with other regions of the refrigerant circuit, the restrictorcontributes little to the volume of the refrigerant circuit andtherefore does not increase the quantity of refrigerant required tooperate the refrigerant circuit to any appreciable degree. Beingdisposed on the side wall, the restrictor is protected from waste heat,which is released by the condenser, which is generally disposed on therear of the appliance. The side wall is therefore a relatively coolregion of the refrigerator housing and allows efficient additionalcooling of the refrigerant circulating through the restrictor.

The restrictor is preferably disposed in the side wall between an outerskin and an insulating layer of the same in such a manner that it isprotected and not visible from the outside. In order to be able toabsorb and pass on the heat from the restrictor quickly, the outer skinof the side wall is preferably metallic.

The restrictor is preferably bonded to the outer skin, to ensure that itremains in heat-conducting contact with the outer skin when theinsulating layer is applied during assembly of the refrigerator. Theinsulating layer is preferably produced in the technically standardmanner by allowing synthetic resin foam to expand in a hollow space inthe housing delimited by the outer skin.

Fast and simple bonding of the restrictor and outer skin can be achievedwith the aid of adhesive tape.

In order to prevent heat being introduced into the evaporator by way ofthe restrictor, preferably only an upstream segment of the restrictor isdisposed on the side wall.

A downstream segment of the restrictor can be positioned in the knownmanner instead in a suction tube leading from the evaporator to thecompressor.

In order to keep the pressure drop in the refrigerant small, at least inthe upstream segment of the restrictor, this latter preferably has alarger cross section than the downstream segment. As this upstreamsegment should not increase the volume of the refrigerant circuitsignificantly, it is preferable for the upstream segment to have a freediameter of less than 1 millimeter.

In order to allow efficient cooling of the refrigerant between its exitfrom the condenser and entry into the evaporator, the upstream segmentpreferably has a length of at least 1 meter. In practice the length ofthe upstream segment will be up to 2 meters in a household refrigeratorof standard size.

For assembly of the refrigerator it is expedient if the downstreamsegment and the upstream segment of the condenser are joined to oneanother outside an insulating layer of the side wall.

The refrigerant circuit preferably has a dryer, the refrigerant supplyline of which is connected to the upstream end of the restrictor on theside wall for flow purposes.

Further features and advantages of the invention will emerge from thedescription which follows of exemplary embodiments with reference to theaccompanying figures, in which:

FIG. 1 shows a perspective view of an inventive household refrigeratorfrom the front; FIG. 2 shows a perspective view of the refrigerator fromthe rear; FIG. 3 shows a plan view of a section of sheet with arestrictor segment fastened thereto, which forms an outer skin of a sidewall of the refrigerator; and

FIG. 4 shows a diagram of the refrigerant circuit of the refrigerator.

FIGS. 1 and 2 show perspective views of a counter-height householdrefrigerator 1. A thermally insulating housing of the appliance is madeup of an essentially cuboid carcass 2 and a door 3, which togetherdelimit a storage chamber 4. The carcass 2 has a structure that is knownper se, with a plastic deep-drawn inner container 5, an outer skinjoined together from a number of elements and a polyurethane foaminsulating layer filling an intermediate space between the innercontainer 5 and the outer skin. The elements of the outer skin includetwo sheet sections 6, which extend in each instance over a side wall ofthe carcass 2 and are connected to the inner container 5 at a frontframe 7 of the carcass 2 facing the door 3.

A machine chamber 8 is cut out at the rear of the carcass 2 close to thebottom and holds a refrigerant compressor 9. A condenser 10 is connectedto a pressure connector of the compressor 9. The condenser 10 is shownin FIG. 2 as a wire tube heat exchanger mounted on a rear wall of thecarcass 2 above the machine chamber 8 but other models of the condenser10, in particular as a compact finned tube heat exchanger alsoaccommodated in the machine chamber 8 and force-cooled by a fan, arealso possible. A downstream connector of the condenser 10 is connectedby way of a sleeve 11 to a restrictor tube 12, which extends in a loopedmanner on the inside of one of the sheet sections 6 facing theinsulating layer.

The sleeves 11, 16 allow the appliance 1 to be assembled, in that,before the sheet sections 6 are joined to the inner container, therestrictor 12 is fastened to one of the sheet sections 6, the carcass 2is joined together so that the ends of the restrictor 12 are exposed inthe machine chamber 8 and the carcass is then foamed and finally therestrictor 12 is inserted into the refrigerant circuit with the aid ofthe sleeves 11, 16.

FIG. 3 shows a perspective view of the inside of the sheet section 6with the restrictor tube 12. The section 6 comprises a flat centralplate 13, which is provided to form the outer skin of a side wall of thecarcass 2 and to which the restrictor tube 12 is fastened with the aidof adhesive tape strips 14. Webs 15 angled away from the central plate13 extend in the finished appliance 1 to its front frame 7 or its rearand are connected there to the inner container 5 or a rear wall plate(not shown) in a foam-tight manner.

Again with reference to FIG. 1 a second sleeve 16 disposed in themachine chamber 8 connects the restrictor tube 12 to a second, narrowerrestrictor tube 17, which traverses the insulating layer of the carcass2 to ensure that the evaporator 18 is disposed in close thermal contactwith the storage chamber 4. As shown schematically in FIG. 4, therestrictor tube 17 passes directly along the surface of a suction tube19, which passes from the evaporator 18 to the compressor 9, or withinsaid suction tube 19.

Because a tube with a small internal diameter, typically approx 0.8millimeters, is used for the restrictor tube 12, the volume of therefrigerant circuit as a whole changes little—despite the restrictortube 12 being typically 1 to 2 meters long—compared with a conventionalrefrigerant circuit of a refrigerator of the same size and therefore thequantity of circulating refrigerant required for efficient operationalso changes little. As the restrictor tube 12 runs along the centralplate 13 at a distance from the web 15 connected to the inner container5, the flow of heat from the restrictor tube 12 to the storage chamber 4by way of the connection between sheet section 6 and inner container 5is negligible. The restrictor tube 12 is shielded from heat emitted fromthe condenser 10 by its spatial distance from the condenser 10.Therefore it is possible to achieve more efficient cooling of therefrigerant with the restrictor tube 12 than by enlarging the condenser10 by the volume of the restrictor tube 12.

The appliance 1 is preferably positioned in such a manner that the sidewall containing the restrictor tube 12 is exposed so that heat emittedfrom the restrictor tube 12 can be passed quickly to the environment.The invention can however also be used—if only with little scope—in arefrigerator with a concealed side wall, for example a built-inappliance or a counter-height appliance flanked at the sides by otherobjects. The sheet section 6 here operates as a thermal storage unit,which absorbs heat from the restrictor tube 12 while the compressor 9 isoperational and drives refrigerant circulation. In a subsequent stoppagephase of the compressor the heat of the sheet section 6 can also bedistributed to the environment with such a refrigerator.

1. A refrigerator, in particular a household refrigerator, having athermally insulating housing (2, 3), which encloses a storage chamber(4), and a refrigerant circuit, which comprises a compressor (9), acondenser (10), a restrictor (12, 17) and an evaporator (18), whichcools the storage chamber (4), characterized in that the restrictor (12,17) is disposed at least partially on a side wall of the housing (2). 2.The refrigerator as claimed in claim 1, characterized in that therestrictor (12, 17) is disposed on the side wall between an outer skin(6) and an insulating layer of the side wall.
 3. The refrigerator asclaimed in claim 2, characterized in that the restrictor (12, 17) isbonded to the outer skin (6), in particular by adhesive tape (14). 4.The refrigerator as claimed in one of the preceding claims,characterized in that the restrictor (12, 17) comprises an upstreamsegment (12) and a downstream segment (17) and the part of therestrictor disposed on the side wall is the upstream segment (12). 5.The refrigerator as claimed in claim 4, characterized in that thedownstream segment of the restrictor (12, 17) is positioned in a suctiontube (19) leading from the evaporator (18) to the compressor (8).
 6. Therefrigerator as claimed in claim 4 or 5, characterized in that thedownstream segment (17) has a smaller cross section than the upstreamsegment (12).
 7. The refrigerator as claimed in one of claims 4 to 6,characterized in that the upstream segment (12) has a free diameter ofless than 1 mm.
 8. The refrigerator as claimed in one of claims 4 to 7,characterized in that the upstream segment (12) has a length of at least1 m.
 9. The refrigerator as claimed in one of claims 4 to 8,characterized in that the downstream (17) segment and the upstreamsegment (12) are joined to one another outside an insulating layer ofthe side wall.